Efinaconazole is the international non-proprietary name of compound (2R,3R)-2-(2,4-difluorophenyl)-3-(4-methylene-1-piperidinyl)-1-(1H-1,2,4-triazol-1-il)-2-butanol, having formula (I):

Efinaconazole is an antifungal drug, generally used in the treatment of onychomycosis.
Other molecules with antifungal activity are also known, having structure similar to that of efinaconazole, for example those described in WO2011/099804.
EP2612859 describes a synthesis of efinaconazole according to the following scheme

Reproducing such a synthesis involves problems, in particular due to the difficult availability of 4-methylenpiperidine and the volatility thereof, because of which it is possible that said compound evaporates during the long reaction time. Furthermore, the Applicant of the present application tried to reproduce some of the examples described in EP2612859, however without reproducibly obtaining the good yields and purities indicated in said document itself and moreover having to work in a pressure reactor to avoid the evaporation of 4-methylenpiperidine.
Because of these drawbacks, it is understood that there is a need to find novel syntheses of efinaconazole that give good results in terms of yield and purity and are also industrially pursuable, without the need to resort to complex equipment.